Worcester Bosch 24CDi CH issue with no lockout but HW is fine (video link)

[smg496]

Hello everyone, so I have an old WB 24CDi with a CH fault (HW seems fine).

The problem was only apparent occasionally after reaching temperature last winter but now from cold it continually attempts to go through the ignition cycle but mostly fails but with the occasional full ignition but only for a few seconds.

It doesn't lock out with a flashing red light fault but just continues to go through the cycle indefinitely.

The fan spins up at each ignition attempt and then switches off when ignition fails and does this process continually as can be heard in the video link.

My first thought was vacuum tubes or switch but with stable HW I'm guessing not.

Any suggestions on the likely cause so I can pass this on to my GSR engineer to minimise costs of return visits?

Tube to fan hard/split (see photo) but replacement did not fix the issue.

17.10.2023.mp4

drive.google.com

 

[cross thread]

Forum rules don’t allow gas related advice sorry

 

[smg496]

Thanks, my post was poorly worded, appreciate why advice is not allowed so edited, any suggestions of the likely issue so I can pass this on to my engineer would be great to save cost of potential multiple visits as he's not local.

 

[CBW]

Sorry, but that’s similar. If your engineer is good enough, they should be able to rectify the fault.

 

[smg496]

Thanks, I am now confused though, I'm certainly not asking for advice on how to repair the fault but simply for discussion on what could be causing this issue.

My background is aerospace engineering and I naturally have a curious mind so problem solving then passing on the information to my engineer prior to booking him in has always served me well.

I ask this with complete respect, is there any way to ask on this forum what is likley causing this issue?

 

[smg496]

Quick follow up in case this is useful for anyone in the future, turned out to be a board issue with two overheated resistors, did well for nearly 25 years though!